The present invention relates to a chrominance signal processing apparatus and method for providing optimal color processing according to the hue of the color image data. Red, green and blue signals are input to a chroma composition ratio determination circuit that generates and outputs the RGB color composition ratio (.alpha.:.beta.:.gamma.). A chroma suppression luminance signal generating circuit then generates a chroma suppression luminance signal Ya based on the RGB signals and the color composition ratio. A chroma suppression gain determination circuit outputs the gain for the chroma suppression luminance signal based on a table in which output gain setting values corresponding to the chroma suppression luminance signals are recorded. Multipliers then multiply input color-difference signals Cr, Cb by the gain and output a suppressed color-difference signals (Cr.times.G, Cb.times.G) according to the color composition ratio (.alpha.:.beta.:.gamma.).